Re: [PATCH v8 10/10] integrity: support EC-RDSA signatures for asymmetric_verify

[Mimi Zohar]

> > diff --git a/security/integrity/digsig_asymmetric.c
b/security/integrity/digsig_asymmetric.c
> > > index d775e03fbbcc..99080871eb9f 100644
> > > --- a/security/integrity/digsig_asymmetric.c
> > > +++ b/security/integrity/digsig_asymmetric.c
> > > @@ -104,9 +104,16 @@ int asymmetric_verify(struct key *keyring, const char *sig,
> > >  
> > >  	memset(&pks, 0, sizeof(pks));
> > >  
> > > -	pks.pkey_algo = "rsa";
> > >  	pks.hash_algo = hash_algo_name[hdr->hash_algo];
> > > -	pks.encoding = "pkcs1";
> > > +	if (hdr->hash_algo == HASH_ALGO_STREEBOG_256 ||
> > > +	    hdr->hash_algo == HASH_ALGO_STREEBOG_512) {
> > > +		/* EC-RDSA and Streebog should go together. */
> > > +		pks.pkey_algo = "ecrdsa";
> > > +		pks.encoding = "raw";
> > 
> > IMA signatures are stored as xattrs, making them persistent. ÂSupport
> > for streebog was upstreamed in linux-5.0. ÂThis change would break
> > existing systems using streebog. ÂAs long as this is not yet a concern
> 
> In what sense it would break systems?

For example, if executable files are currently labeled with
rsa/streebog signatures, then enforcing file data integrity I assume
would break if the kernel uses ecrdsa/streebog.

Mimi

> 
> Unless kernel crashes or signature is recognized as valid, I think, it should
> not be called a break.
> 
> > Reviewed-by: ÂMimi Zohar <zohar@xxxxxxxxxxxxx>
> 
> Thanks!
> 
> > 
> > > +	} else {
> > > +		pks.pkey_algo = "rsa";
> > > +		pks.encoding = "pkcs1";
> > > +	}
> > >  	pks.digest = (u8 *)data;
> > >  	pks.digest_size = datalen;
> > >  	pks.s = hdr->sig;
>